.\" Copyright (c) 2007 Joseph Koshy.  All rights reserved.
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.Dd November 24, 2007
.Dt PMC_CONFIGURE_LOGFILE 3
.Os
.Sh NAME
.Nm pmc_configure_logfile ,
.Nm pmc_flush_logfile ,
.Nm pmc_writelog ,
.Nm pmc_close_logfile
.Nd log file management
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Ft int
.Fn pmc_configure_logfile "int fd"
.Ft int
.Fn pmc_flush_logfile void
.Ft int
.Fn pmc_writelog "uint32_t userdata"
.Ft int
.Fn pmc_close_logfile void
.Sh DESCRIPTION
The functions manage logging of
.Xr hwpmc 4
events.
.Pp
Function
.Fn pmc_configure_logfile
is used to turn on and turn off logging.
If argument
.Fa fd
is a valid file handle returned by a prior call to
.Xr open 2
or
.Xr socket 2
then performance events will be logged to the file corresponding
to the specified handle.
If the value of argument
.Fa fd
is -1 then logging will be stopped after any pending data is flushed.
.Pp
Function
.Fn pmc_flush_logfile
will force all log data queued inside the
.Xr hwpmc 4
driver to be written out.
.Pp
Function
.Fn pmc_writelog
will append a log entry containing the value of argument
.Fa userdata
to the log file.
.Pp
Function
.Fn pmc_close_logfile
will flush all pending log data and close
.Xr hwpmc 4 Ns Ap s
side of the stream.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
A call to
.Fn pmc_configure_logfile
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EAGAIN
The
.Xr hwpmc 4
driver was not able to create a helper process due to system limits
being reached.
.It Bq Er EBUSY
Function
.Fn pmc_configure_logfile
was called with a log file already configured.
.It Bq Er EINVAL
Function
.Fn pmc_configure_logfile
was called with an argument of -1 without a log file being previously
configured.
.It Bq Er ENOMEM
The system encountered a memory shortage when servicing this request.
.El
.Pp
A call to
.Fn pmc_flush_logfile
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
Function
.Fn pmc_flush_logfile
was called without a log file being previously configured.
.El
.Pp
A call to
.Fn pmc_writelog
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
Function
.Fn pmc_writelog
was called without a log file being previously configured.
.It Bq Er ENOMEM
The system encountered a memory shortage when servicing this
request.
.El
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr hwpmc 4
